Method of and means for driving electric railway cars



May 2, 1933.

Flq. i. 1.01 10'). 10'?! 104 105106 107 108 109 1.10 11 E. H. SCOFIELD 1,907,126

METHOD OF AND MEANS FOR DRIVING ELECTRIC RAILWAY CARS Filed April 18, 1929 4 Sheets-Sheet l 1N MUL PLE \VXNDINGS Edward H. Scofiald May 2, 1933. E sgo 1,907,126

METHOD OF AND MEANS FOR DRIVING ELECTRIC RAILWAY CARS Filed April 18, 1929 4 Sheets-Sheet 2 Fig. 5

'3 57 57 57 57 '57 57 7 as as I 58 58 58 1-56 158 158 158 1'58 158 157 157 m m m 157 Fig. 2

Edward H. Scofi eld gmez Mtg May 2, 1933. E. H. SCOFIELD 1,907,126

METHOD OF AND MEANS FOR DRIVING ELECTRIC RAILWAY CARS Filed April 18, 1929 4 Sheets-Sheet 4 Fig. 7

mentor Fig.6. I Edward H.5cofm1d wus Patented May 2, 1933 SCOFIELD, OF MINNEAPOLIS, MENNESOTA EDYVARD METHOD OF AND MEANS FOR DRIVING; ELECTEIC EAZLVJ'AY CAR-S Application filed. April 18,

My invention relates to the method of and means for drlving electrlc railway cars and particularly to the application of electric power for traction purposes.

An object of the invention resides in providing a method and means whereby a higher rate of acceleration may be procured and the ultimate time required for bringing the car up to any desired speed out down.

Another object of the invention resides in providing a method and means for driving electric railway cars in which a relatively smaller amount of controller resistance is employed than otherwise used,

whereby the heat losses may be reduced and the efficiency of operation of the railway car appreciably increased.

A still further object of the invention resides in providing a method of and means for driving electric railway cars in which one'half the number of motors ordinarily used for driving a railway car may be employed or in the alternative if the same number of motors be used, the motors designed for and used on one-half the customary voltage.

Another object of the invention resides in providing a method of and means for driv- 1ng electric railway cars in which greater torque may be procured upon starting when the speed is the lowest and lower torque utilized as the car gains in speed, without resorting to mechanical reduction in speed through changes in gear ratios.

An object of the invention resides in providing two motors, each having the usual field winding and each having two armature windings.

A still further object of the invention resides in the method of driving the railway car with said motors which consists in successively connecting the motors in series ad in parallel and at appropriate times in similarly connecting the armature windings of said motors in series and parallel to most effectively accelerate the car and bring the same up to running speed in the shortest time.

Another object of the invention resides in the method of driving railway cars with 1929. Serial No. 356,063.

motors having double armature windings in which all of the fields and armature windings of all of the motors are first connected in series, in which the motors are next conected in multiple ture wirdin s of the several motors are subsequent y connected in multiple.

A feature of the invention resides in the method of applying electric power to railway cars which consists in the successive carrying out of the various steps hereinafter more fully described in detail.

0 of the invention reside the details of construction thereof and i the novel combination and arrangement 0 pai" l ter illustrated or described.

the drawings:

1 is a wi 'ng diagram illustrating embodiment I invention.

* 2 is a long cudinal sectional view of the motors used with my invention. Fig. 3 is a diagrammatic view illustrating various connections of the motor pro through the operation of the controller CliS" OSCl in operation of the condiate positions thereof.

"immatic view similar to rting the various con- )rocured through the operation of the control positions thereof.

6 is a diagrammatic view of a number of curves illustrating the operating characteristics of railway motor cars procured with my invention.

Fig. 7 is a diagrammatic view of a numof curves illustrating the acceleration procir'able with railway cars equipped with my invention.

lVith the present 'iethods of driving railway cars by electric power, two or more meters used for each truck which are successively connected in series and multiple with the introduction of suitable resistances at proper intervals. With such systems, for a given current consumption, the maxin'ium,

and in which the armai i P l at some of the 1n1t1al ler at the remaining 8 tractive effort remains the same for all car speeds unless the gear ratio between the motor shaft and axle are changed, as by some mechanical speed changing device. Such devices are exceedingly undesirable for electric railway work due to both the mechanical problems involved in the design of mechanical gear shifts, as well as the ditiiculties and complications encountered in operating railway cars equipped with such devices. In addition, the usual systems require a relatively high gear ratio between the motor shaft and axle which either requires worm gearing or other gearing of extremely large proportions. My invention overcomes these difficulties by providing a method of and means for driving electric railway cars by which the desired results are accomplished without the use of mechanically operated speed changing devices.

The motor used with my invention is illustrated in detail in Fig. 3, and is indicated in its entirety at 27. This motor comprises a frame 28 which is formed with end plates 29 and 30 carrying bearings 31 and 32 in which the armature shaft is journalled. Within the frame 28 are attached the usual pole pieces 34 which surround an armature 36 mounted upon the shaft 33. These pole pieces have mounted on them the usual field windings 35. The armature 36 differs from the usual railway motor armature in that the same has two windings 37 and 38 in place of the single armature winding. The winding 37 is connected to a commutator 39 at one end of armature 36, while the winding 38 is similarly connected to another conimutator 40 at the other end of the armature. Both of these commutators have individual sets of brushes 41 and 42 which are connected in the system in a manner to be presently described. The motor 26 may be constructed with a ventilating fan 43 for cooling the same, and the frame 28 may be formed with a number of ventilating openings 44 and 45 through which the air may be circulated through the motor proper, for the purpose of reducing the temperature thereof.

Fig. 1 illustrates in diagrammatic form the wiring for a motor installation employing two motors such as illustrated in Fig. 2, which may be both mounted upon the same truck each to drive two of the wheels thereof or which may be mounted upon two separate trucks. For the sake of clearness, it will be assumed that the installation disclosed includes two separate trucks. In the diagram, the two motors have been designated at 27 and 127 while the two sets of armature windings thereof are designated at 37, 38 and 137, 138, respectively. The corresponding field coils for these two motors are 35 and 135, and in addition to the said motors, two fixed ohmic controller resistances 56 and 156 are employed.

The controller used with the invention is indicated in its entirety at 57 and may be of the drum type arranged to move through a number of positions designated at 101 to 124 respectively. This controller comprises a number of plates 58, 59, 60, 61, 62 and 63 which are arranged upon the controller drum and are insulated from one another and operated in the usual manner. These plates are shown in developed form in Fig. 1, the same being illustrated with a circumferential direction running from right to left, and their axial direction running up and down. These plates, when the controller drum is rotated, are adapted to contact with a number of contacts illustrated in'nncdiately to the left of the plates 58 to 63 which are connected to the motor proper and designated as 64 to 86, inclusive.

The method of wiring the controllers and motors is as follows: The contact 64 is ronnected to the trolley while contact is connected to ground. 'A conductor 87 connects contact 65 with one end of the field winding 35 of motor 27, while the other end of the said motor field coil is connected through a conductor 88 with the contact 71. Contact 66 connects with the contact 86 and also with one end of the field coil 135 of motor 127 through a conductor 89. The other end of the field coil of said motor is connected through a conductor 90 with contact 78. Contact 67 is connected through a conductor 92 with a tap on the resistance 56, which tap may be made to any point along the same to include a part or all of said resistance. This tap is preferably variable, as will become apparent presently. Another conductor 93 connects the contact 68 with a similar tap on the resistance 156. Contact 69 is connected through a conductor 91 with one of the brushes of the armature winding 38 and also with the contact 74. The corresponding brush of the companion winding 138 is connected through a conductor 94 with contact 81. A conductor 195 connects this contact with the contact 76. Both of the other brushes of the armature windings 38 and 138 are connected together and to the contact 84 through a single conductor 95. One end of the resistance 56 is connected through a conductor 96 with the contact 73. The other end of said resistance connected to one of the brushes of the armature winding 37, both of which are connected through a conductor 97 with the contact 70. A conductor 98 is connected to contact 72 and to a tap in the resistance 56. The other brush of armature winding 37 connected through a conductor 99 with the contact 75, which, in turn, is connected to another contact 83, positioned at another location upon the contactor board. One end of the resistance 156 is connected through a conductor 100 with a contact 80,

i r sail while the other'end of said resistance is connected through conductors 142 and 139 with one of the brushes of the armature winding 137 and with the contact 77. A conductor 140 similar to the conductor 98 is connected to the tap on the resistance 156, and fur ther to the contact 79. The other brush of the winding 137 is connected through a conductor 141 with contact 82.

In order to more readily follow the different steps in bringing the motors of the truck up to full speed, the connections or" the various motors as they occur for each step have been diagrammatically illustrated in Fig. 3. The precise manner of connecting the motors is shown for each position of the controller 57 and these positions have been numbered to correspond with the positions indicated on the controller.

In the operation of the device, acceleration of the car is produced as follows. When thecontroller drum is rotated so as to bring the various plates at the circumferential position designated at 101 in the path of the various contacts 64 to 86 inclusive, contacts 64 and 65 are connected together, contacts 71 and 73 connected together, contacts 74 and 75 and 78 and 80 connected together, contacts 81 and 82 connected together, and contacts 85 and 86 connected together. This completes a circuit through the various motors which may be traced as follows. Starting with contact 64, which is connected to the trolley, the circuit may be traced through plate 58, conductor 87, field coil 35, conductor 88, plate 59, conductor 96, all of resistance 56, the armature winding 37 of motor 27, conductor 99, plate 60, conductor 91, the armature winding 38, a branch of conductor 95, armature winding 138, conductor 94, plate 62, conductor 141, armature winding 137, conductor 142, all of resistance 156, conductor 100, plate 61, conductor 90, field coil 135, conductor 89, plate 63, and back to the contact 85, which is connected to ground. In this circuit, all of the armature windings, both of the field coils and all of the two resistances are connected in series with one another. As the controller moves to position 102, contact 72 engages the plate 59 which closes a circuit through contacts 72 and 73 and the conductors 98 and 96, which forms a shunt around part of the resistance 56, cutting out part of said resistance and increasing the current through the motors. At the next position 103, the contact 79 is connected to the contact 80 which similarly cuts out a part of the resistance 156 further increasing the current in both motors. At position 104, contact 70 is also connected to the plate 59 and contact 73 being previously connected to the plate 59 a circuit is formed through the two conductors 96 and 97 which shorts the entire resistance '56, further increasing the current through the motors. At position 105, contact 77 is connected with plate 61 which in a similar manner shorts all of the resistance 156 to further increase the current through the motors. At the same time, the contact 72 connected with the tap in the resistance 56 is disconnected preparatory to a following change in the various contacts. WVhen the controller reaches position 106, contact 0 is disconnected from contact 59 and similarly contact 79 disconnected from plate 61. While the controller remains at this position, which is merely a transition step prior to the cutting of the motors in parallel, all of the resistance 56 is again momentarily reinserted. At position 107, contact 84 is connected to the plate 63 which completes the circuit through the conductor 95 connected to both the armature windings 38 and 138 to ground. At such position, the motor 27 receives the full voltage across both of its armature windings in series, while the entire motor 127 is momentarily shorted through the plate 63 preparatory to being disconnected and subsequently reconnected with full voltage. At step 108, contact 77 is disconnected and at the same time, the contact 86 is disconnected. This has the effect of opening the circuit through the motor 127, and inserting all the resistance 156. At position 109, contact 66 is connected to the plate 58, which brings conductor 89 at trolley potential and connects the motor 127 in multiple with the motor 27 through the conductor 95 to ground. Both motors are now in multiple with full voltage and all of the resistance for each motor and both of the armature windings for each motor are in series, in their respective circuits.

It may be well at this point to retrace the circuit to more fully visualize the relation of the motor windings when the motors are in multiple. Starting with contact 64, which is connected to the trolley, the circuit is traced through plate 58, through contait 65, conductor 89, field coil 35, conductor 88, contact 71, plate 59, conductor 96, all of resistance 56, the winding 37 of motor 27, conductor 99, plate 60, conductor 91, armature winding 38, conductor 95 and plate 63 to the contact 85 and to ground. At the same time, another circuit may be traced from the trolley to plate 58, contact 66, conductor 89, field coil 135, conductor 90, plate 61, conductor 100, all of resistance 156, conductor 142, armature winding 137, conductor 141, plate 62, conductor 94, armature winding 138, conductor 95 and contact 85 to ground. This places both motors in parallel with both armature windings in series and all of the resistances of eacn motor cut in.

As the controller drum is turned, the manipulation of the resistances 56 and 156 is again repeated, as with the motors both in series, in which a part of the resistance 56 is cut out at position 110, part of the resistance 156 cut out at position 111, all of resistance 56 cut out at 112, and all of the resistance 156 out out at position 113, leaving both motors running in parallel without resistance, and with both armatures of each motor in series in their respective circuits.

At position 114, contact 73 is connected to plate 60. This completes a circuit around the armature winding 37, through the resistance 56 which by passes some of the current normally flowing through said winding, thereby increasing the current flowing through the armature winding 38 and simultaneously increasing the torque of said winding.

At position 115, the same connection is made with respect to the armature windings 137, 138 and resistance 156. At the same time, connection between contact 75 and plate is broken, disconnecting the armature winding 37, altogether and running the motor 27 with the armature winding 38 only. At the same time, the resistance 56 is cut in in its entirety in series with the winding 38.

At position 116, winding 137 is similarly cut out, and the resistance 156 thrown in series with the winding 138. At the same time, a part of the resistance 56 is cut out.

At position 117, part of the resistance 156 is cut out leaving the motor operating with the winding for each motor with part of the resistance in series with each of these windings.

At position 118, the winding 37 is connected to ground with the other art of resistance 56, in series, both of sai windings being now in multiple and the other winding still remaining in series with the other portions of the resistance.

At position 119, the same connection is made with reference to winding 137, bringing both windings of both motors in multiple, and in series with the remainder of resistance 156. At the same time, part of the resistance previously connected with winding 37 is cut out.

At position 120, a similar portion of resistance 156 is cut out from the circuit containing winding 137. During steps 121 and 122, the remaining portions of the resistances 56 and 156 are cut out, bringing the motors in multiple with both windings of each motor also in multiple and without resistance.

If a higher speed is desired, the same can be obtained by further rotating the condurtor drum. At position 123. contact 67 is connected with the plate 58. This completes a circuit through the conductor 92. a portion of the resistance 56, the conductor 88, field, coil 35, and conductor 87 which shunts the field 35 weakening the same and speeding up the motor. At position 124, the same is accomplished with respect to field coil 135 similarly speeding up motor 127.

To more fully comprehend the advantages and operation of the invention, reference may be had to the curves plotted in Figs. 4 and 5. In Fig. 4, two sets of curves are disclosed, of which curves 143, 144, 145, 243 and 244 represent speed curves of the railwa cars, plotted with amperes as abscissas an miles per hour as ordinates. The curves 146, 147 and 246 are torque curves and are plotted with amperes as abscissas and tractive eflort in pounds at the circumference of the driving wheels as ordinates. A. zig-zag curve shown at 148 is a composite speed ampere curve of the railway car acquired by the operation of the controller through the various steps previously described. Of the various curves illustrated, curve 243 represents the usual curve procured with the ordinary electric railway car in which two motors are used connected in parallel The curve 244 shows the performance when the two motors are connected in series. Corresponding with these curves, curve 145 shows the speed attainable with the motors used in my invention connected in series and the armature windings thereof also connected in series. The curve 144 shows the performance when the motors are connected in multiple with the pairs of windings of each particular motor still remaining in series. Curve 143 shows the speed performance when the motors used with my invention are both connected in multiple and each pair of windings connected in multiple. Corresponding to these curves, the curve 246 represents the single torque curve available with the ordinary railway car. Curves 146 and 147 corresponding therewith show two values of torque attainable with my invention.

In Fig. 5 I have shown acceleration curves. illustrating the speed acquired for travel of the railway car for certain units of time and space. Of these curves, curves 249 and 250 represent the performance with the ordinary type of railway car in which two motors are used, curve 249 being the curve for the motors in multiple and curve 250 for the motors in series. Corresponding therewith, curves 149 and 150 and 151 represent the performance curves of a railway car equipped with two motors constructed and operated in accordance with my invention. Of these curves, curve 151 represents the performance of the car with both motors in series and the armature windings of both motors all in series. (urve 150 represents the performance of the two motors in multiple with the armature windings of each motor still in series.

Curve 149 represents the performance when both motors are in multiple, and the armature windings of each motor are connected in multiple. Along the Various curves 149, 150, 151, 249 and 250, reference marks have been placed indicated at 158 opposite which certain figures appear. These figures designate the number of seconds elapsing after the initial operation of the controller and assists in comparing the performance of the railway car with the two systems illustrated. The various curves illustrated are plotted to feet as abscissas and miles per hour as ordinates. In addition to the reference marks, 153, the various curves is provided with the reference marks 154 which correspond to the various positions or steps of the controller proper. These various positions are made to conform to the controller positions. The curve 155 represents a coasting curve, while the curve 157 represents a braking curve.

A study of the curves in Fig. 4 shows that two values of tractive effort can be procured for any value of current with my invention, thereby permitting of greatly increasing the torque while starting when the greatest tractive elfort is desired. In addition, the motors may be operated on three speed curves varying in range considerably over the standard speed curves, thereby requiring a much smaller amount of resistance with such motors. The composite curve 148 shows the actual current used per motor as the car is being accelerated, illustrating t e variation in operating current to procure-the desired acceleration. A study of the curves in Fig. 5 illustrates the increased acceleration obtainable with my invention as compared with the ordinary type of electric railway motor. In addition, these curves, while taken in conjunction with the braking and coasting curves, show the saving of power possible with my invention as well as the comparatively shorter length of time required to cover a given distance. The curves 149, 150 and 151 show the speed which would be obtained by permitting the motors to run over the specified periods of time, either connected in multiple with the armature windings in multiple or in multiple with the armature windings in series, r in series with the armature windings in series. The correv sponding curves 249 and 250 show the performance with the standard or ordinary form of railway car with the motors connected in multiple or in series. Applying the coasting curves 155 to any part of these various curves v149 01 249, it will be noted that the current must remain turned on for a considerable number of seconds longer with the standard equipment than with that utilized in my invention, thereby greatly economizing on power consumption. The same is also true in conjunction with the braking curve 157, though perhaps not so marked.

The advantages of my invention are manifest. The system is exceedingly effective for the desired purpose and results in economy of power. Rapid acceleration may be readily had when desired, making the installation particularly adaptable for use in congested city trafiic. Due to the two values of tractive effort possible with my invention, the railway car can be put under way a lot more rapidly than with the ordinary equipment, and considerably more t-ractive effort is available for the purpose. With my invention, larger motors may be utilized at a comparatively smaller cost per horse power, thereby reducing the operating expense and depreciation in connection with the same. With my invention, a smaller gear ratio is required than required under ordinary conditions, thereby simplifying the power transmission problem and reducing the cost of the transmission gearing. here a single motor is used for each truck, as is possible with my invention, an interlock may be had between the two wheel axles, so as to increase the traction obtainable at the wheels of the truck or for the purpose of acceleration and braking. Where two motors or more per car are desired, the motors may be built for one-half the voltage ordinarily employed, thereby simplifying the insulating commutation and conductor problems in conjunction with the design of the motors. lVith my invention, less resistance is required for insertion in series with the motors upon starting, resulting in reduction in heat losses and correspondingly increase in efficiency of the system.

Changes in the specific form of my invention, as herein disclosed, may be made within the scope of what is claimed without departing from the spirit of my invention.

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

1. The method of driving vehicles equipped with a plurality of series motors having dual armature windings, which consists in first connecting all of the motors and all of the armature windings in series, in thereafter connecting the motors in multiple, and in successively connecting the armature windings of each motor, one pair at a time, in multiple.

2. The method of driving vehicles equipped with plurality of series motors having dual armature windings, which consists connecting all of the motors and all the armature windings in series, in thereaf connecting the motors in multiple, in connecting the motors in multiple with one of the armature windings thereof disconnected, and in subsequently connecting the disconnected armature winding in multiple with its companion winding.

3. In combination, a motor having a field coil and an armature, said armature being in series across said line, means for shunting said resistance, means for connectin said field coil, resistance and one of sai armature windings across the line, means for thereafter shunting said resistance a second time, means for subsequently connecting said field coil in series with said resistance and said armature windings in multiple, and means for thereafter shunting the resistance a third time.

4. The method of driving vehicles equipped with two series motors havin dual armature windings, which consists in connecting the motors in series with the armature windings in series, in thereafter connecting the armature windings of each motor, one at a time, in multiple.

5. The method of driving vehicles equipped with a plurality of series motors having dual armature windings which consists in connecting the motors in multiple with the armature windings of each motor in series and in thereafter connecting the armature windings of each motor, one pair at a time, in multiple.

6. The method of driving vehicles equipped with a motor having dual armature windings and a field coil therefor, which consists in connecting the two windings of the armature in multiple with one another and in series with the field coil and in thereafter connecting a resistance in multiple with said field coil and in series with said armature windings in multiple.

7. The method of driving vehicles equipped with two motors having dual armature windings and field coils therefor, which consists in connecting the motors in multiple with the two windings of each armature in multiple with one another and in series with the respective field coils therefor and in thereafter successively connecting resistances in multiple with said field coils and in series with the respective armature windings.

8. In combination, a motor having a field coil and an armature, said armature being provided with a pair of windings, two resistances, a power line, a controller including means for connecting said field coil in series with both of said armature windings in series, means for connecting a resistance in multiple with one of said armature windings, means for subsequently disconnecting the same armature winding from its companion winding, means for thereafter connecting a resistance in series with said disconnected armature winding and means for thereafter connecting said disconnected armature winding with its resistance in multiple with said other armature winding.

9. In combination, a motor having a field coil and an armature, said armature being provided with a pair of windings, two resistances, a power line, a controller including means for connecting each of said armatures in series with one of said resistances and in connecting said groups in parallel with one another and jointly in series with said field coil across said line and a means for subsequently shunting said resistances one at a time.

10. In combination, a motor having a field coil and an armature, said armature being provided with a pair of windings, a resistance, a power line, a controller including means for connecting one of said windin in series with said resistance and in multip e with the other winding and for further connecting said multiple circuits in series with said field coil and across the line and means for thereafter shunting said resistance.

11. The method of driving vehicles equipped with two series motors having dual armature windings and field coils therefor from a power line, which consists in connecting the motors in multiple across said line with the armature windings of each motor in series with one another and in series with a resistance and in subsequently shunting said resistances one at a time.

12. The method of driving vehicles equipped with two series motor having dual armature windings and field coils therefor from a power line which consists in connecting the motors in multiple across said line with the armature windings of each motor in multiple with one another and in series with said resistance and in thereafter shunting out said resistances one at a time.

13. The method of driving vehicles equipped with two series motors having dual armature windings which consists in connecting the motors in parallel with the armature windings of each in series and in thereafter shunting out the armature Windings of each of said motors, one at a time.

14. The method of driving vehicles equipped with two series motors having dual armature windings, which consists in connecting the motors in series with the armture windings in series and in thereafter connecting said motors in multiple, one at a time with the armature windings of each of the motors in series.

15. The method of driving vehicles equipped with two series motors having dual armature windings, which consists in connecting the motors in multiple with the armature windings in series and in thereafter connecting the armature windings of each motor, one at a time, in multiple.

16. The method of driving vehicles equipped with two motors having dual armature windings and field coils therefor from a power line, which consists in connecting one motor with its armatures and field coils in series across said power line and in thereafter connecting one armature of said other motor and its field coils in series across said power line and in subsequently connecting one armature of each of said motors and its field coil in multiple across said line.

17. The method of driving vehicles equipped with two motors having dual armature windings and field coils therefor from a power line, which consists in connecting the motors in multiple across said line with the two armature windings of each motor in series with one another and with the field coils of said motors and in subsequently shunting the circuits through one of the armature windings about the other of said armature windings, one at a time.

18. In combination, two series motors each having a field coil and an armature, said armatures being provided with pairs of windings, a resistance for each motor, a power line and a controller including means for connecting said motors and their resistances in multiple across said. line with said armature windings in series and in c0nsecutively shunting said resistances.

19. The method of driving vehicles equipped with two motors, each having dual armatures and a field coil from a power line, which consists in connecting all of the armature windings and field coils in series across said power line, in subsequently connecting each of said field coils in series with both of its respective armature windings across said power line, and in thereafter connecting the armature windings of each motor in parallel with one another and in series with the field winding thereof across the line.

In testimony whereof I have afiixed my signature to this specification.

EDWARD H. SCOFIELD. 

